Electric clocks on continental Europe that are steered by the frequency of the power system are running slow by up to 5 minutes since mid-January according to a news release from the European Network of Transmission System Operators for Electricity ('entsoe'). The transmission system operators (TSOs) will set up a compensation program to correct the time in the future.
Many electric clocks rely on the transmission system frequency to provide a source that minimises long-term drift. Quartz crystals have good short term stability, but dreadful long term stability, so plant and machinery that requires power to be turned on or off at a specific time each day without maintenance over a long period historically used clocks slaved to the power-system frequency, which is kept long-term stable by the system operators to prevent problems in power generation and transmission across national and supra-national grids - for example, attempting to switch supplies to generators that are not synchronised to the grid frequency can severely damage the generator.
It is normal for transmission system operators to allow the frequency to drop slightly at periods of high demand, thus slowing clocks, but usually, the frequency is increased during periods of low demand to ensure the long-term average frequency remains stable.
(Score: 2) by RamiK on Wednesday March 07 2018, @12:47AM
Shitty consumer quartz crystals kept in-doors (temperature and humidity wise) on the typical EU national grid barely drift half a minute a month (10ppm/32kHz) and won't fail for a good decade. e.g. Look in eBay for "programmable relay switch timer 220v 16a" and you'll find 4$ wall mounted units that let you turn your water heater on and off and keep the time with 5ppm RTCs. There's 7$ units going into the rail (DIN or whatever) with all the implied protections that do 30amps.
Industrial RTCs go well into the 1.5-3ppm between -50C to +80C. Military grade RTCs are said to lower this to 0.5-1.0ppm between -50C to 90C.
Honestly you'd think after making a career off cleaning up harmonics and correcting the power factor, industrial EEs will know better than to trust the grid to keep timing and would switch to a digital solution.
compiling...